The invention concerns a device for conveying products, in particular fruits, designed to supply a unit for sorting the said products as a function of predetermined selection criteria.
Operations for calibrating fruits require the individualization thereof with a view to enabling them to be sorted as a function of selection criteria, such as weight, calorimetric aspect etc. To this end, sorting units include a feed conveyor which is able, from a flow of fruit delivered in bulk for example in a stream of water, to arrange these fruits behind each other so as to enable them to be analyzed individually and subsequently selected.
Such a feed conveyor is in particular described in the French patent FR-2 716 874 in the name of the applicant and includes a plurality of rollers, each mounted freely in rotation about a transverse rotational axle carried by an endless chain and extending orthogonally with respect to the latter, the said rollers being spaced so that two successive rollers define a housing between them for a product and consisting of parallel discs disposed orthogonally with respect to the rotational axle.
According to this patent, each roller additionally consists of four parallel discs defining a concave-shaped surface for supporting the products two lateral discs of the same diameter and two central discs with the same diameter less than that of the lateral disc.
It has however been found that such a feed conveyor, has several disadvantages, as do all feed conveyors existing at the present time. Indeed, these feed conveyors are dedicated to fruits with substantially similar dimensions for which the diameter and distance between the axles of the rollers are determined. On account of this, in practice, each sorting-unit is designed to carry out sorting of a given type of fruit, without the possibility of using it for other fruits with different sizes and/or shapes.
Moreover, current feed conveyors have proved to give a relatively low yield, namely a low loading rate, in particular for high feed rates.
Finally, current conveying devices also lead in particular for high feed rates, to the formation of doubles, consisting of the positioning of two fruits between two rollers, which results in the impossibility of sorting the said fruits forming the doubles in a selective manner.
In practice, the last two disadvantages lead to a limitation of the feed rates to the sorting unit and hence to non-optimized yields thereof.
The present invention aims at overcoming all these disadvantages and its object is essentially to provide a conveying device for feeding a sorting unit having an optimal throughput and reliability, and which can be used for the transport of products with very different sizes and/or shapes.
To this end, the invention concerns a conveying device, wherein:
each roller has two parallel discs spaced by a distance (d) and having the same diameter, carried by a transverse shaft mounted freely in rotation about the rotational axle,
it comprises two fixed lateral slides disposed symmetrically either side of the discs of the rollers, the said slides being inclined in the direction of the discs at an angle (xcex1) with respect to a plane (P) passing through the rotational axis of the rollers and each being disposed so as to present a lower edge extending close to the adjacent disc and the transverse shaft of each roller, and to form a bottomless chute, with a section in the shape of a truncated V, having a depth greater than the radius of the discs.
Such a conveying device thus includes two fixed lateral slides extending either side of the rollers substantially as far as the transverse shaft thereof and consisting of lateral surfaces for supporting the products which, associated with the shape of the said rollers composed of two discs of the same diameter, causes each of the products to be centered between two rollers.
In practice, it has been found that such a design enables, with a high feed throughput, fruits to be arranged one following the other between different rollers with an optimum filling rate for the conveying device.
Moreover, it has also been found that such a conveying device can transport, with the same yield and the same reliability, products with very different shapes and sizes which can in particular vary from a single to a triple size.
According to another characteristic of the invention, each slide is inclined at an angle (xcex1) substantially comprised between 45xc2x0 and 48xc2x0, this range of angles proving, in point of fact, the best compromise to ensure the transport of small-products such as for example of the order of 30 to 40 millimetres and also the transport of products with much larger sizes, for example greater than 100 millimetres.
As a preferred example, in particular intended for the production of conveying devices for feeding fruit sorting units, each disc of the rollers has a diameter of the order of 80 to 85 millimetres, the said disc being separated transversely by a distance (d) of the order of 15 to 25 millimetres, and the distance between the rotational axles of the rollers being of the order of 95 to 105 millimetres. Such dimensions prove to be suitable for transporting fruit of which the size may vary within a range substantially comprised between 35 mm and 110 mm.
The lower edge of the lateral slides preferably include in addition, an outer hem so that a sharp edge is not presented which would damage the products.
According to another characteristic of the invention, the conveying device includes a rolling surface for the rollers able to produce rotation of the said rollers about their rotational axles
This driving of the rollers in rotation leads, in point of fact, to improved distribution of the products between the said rollers.
Moreover, this rolling surface for the rollers advantageously consists of an endless belt associated with drive means capable of driving it with an adjustable speed of movement. The ability to adjust the speed of movement of the continuous belt makes it possible to modify the direction of rotation of the rollers and their rotational speed in one or other direction of rotation. Thus, according to the size and shape of the products, it is possible to favour:
either the loading capabilities of the conveyor by ordering the rollers to rotate in the same direction as the direction of motion of the said conveyor, obtained with a speed of movement of the belt less than that of the conveyor,
or the xe2x80x9cdoublingxe2x80x9d capabilities of the conveyor by ordering the rollers to rotate in the opposite direction to the direction of motion of the said conveyor, obtained with a speed of movement of the belt greater than that of the conveyor.
According to another characteristic of the invention, the conveyor has a so-called analytical horizontal portion of its path, equipped with means for analyzing the external appearance of the product, the conveying device including, in the region of this horizontal analytical portion of its path, a rolling surface for the rollers capable of producing rotation of the said rollers about their rotational axles.
Moreover, this rolling surface advantageously consists of an endless belt associated with drive means capable of driving it with a speed of movement greater than the speed of movement of the conveying device. This endless belt thus enables the rollers to be driven and hence the products housed between the latter in a direction of rotation opposite to the direction of movement of the conveyor, which favours analysis of all the surface of the said products.
According to another characteristic of the invention, the slides are interrupted over a predetermined length along the horizontal portion of the path, upstream from the means of analysis.
This interruption of the slides makes it possible to remove any product which may be found xe2x80x9cdoubledxe2x80x9d between two rollers with a view to recycling it.